Data transmission speed and quality is an important aspect of data communication systems and networks. Data may be transmitted according to different data transmission protocols. Multi-level signal modulation, such as PAM4 signal modulation, is used for enhancing of data rate in bandwidth limited data communication channels. A critical transmitter parameter of a transmitter is the linearity of the output signal generated by the transmitter. That is, the deviation of each signal level in an analog transmitter output from its expected value should be small, where an expected value can be derived from positions of other levels. Output linearity can be affected by a number of factors, including the quality of the tail current source and the steering factor of input devices.
Integrated circuits enabling data transmission are an important part of the data communication systems and networks. As operating and design characteristics, such as transistor sizes and operating voltages, of integrated circuits continue to change, the performance of a transmitter circuit can be affected. Because output linearity affects the bit error rate of received data, circuit arrangements that improve output linearity are beneficial.
Accordingly, circuits and methods of providing improved output linearity of a modulated signal in a transmitter of an integrated circuit are desired.